An old press release says, "The Hydra Club was founded in 1947. A New York club, it was founded in Philadelphia, at that year’s Worldcon, when Lester del Rey said to Frederik Pohl, talking about spending time with fellow sf people, a novelty, since the recently ended war had broken up established sf groups, “This was fun. We ought to do it more often.” Back in New York, they did. They each rounded up some friends — totaling nine in all, which accounts for the name, which was borrowed from that of a legendary Greek monster with nine heads — and the club was formed."

This is a club page. Please extend it by adding information about when and where the club met, when and by whom it was founded, how long it was active, notable accomplishments, well-known members, clubzines, any conventions it ran, external links to the club's website, other club pages, etc.

When there's a floreat (Fl.), this indicates the time or times for which we have found evidence that the club existed. This is probably not going to represent the club's full lifetime, so please update it if you can!